Unity cost 2.5% of your income, Unreal - 5%(if income is above $1M). There is no free Unity version. There is a version with runtime fee model and if you have less than 100k installations - it is free for you. But if you have more than that - they charge you 2c per installation. It counts repeatable installations of same game and newer versions as well. After community rant in last year - they promised to increase limit to 200k, but refuses to remove this runtime fee.
GD passed that limit long ago. I made some evaluation of download numbers, and only in this year - Unity would have charged him about $4k, about $1k per month, 20% of his income from Patreon. Unity is the most expensive game engine for indie developers. This is why you should avoid using it as much as possible.
But most important part - is development time.
GD is a skyrocket among developers. He gives us new versions every 1-1.5 month. And even big update for new household mechanic - took only two months. And not last part of such speed - HTML + SugarCube. Developing with Unity would take about 3-5 time longer for each update. Even longer with Unreal Engine. These heavy tools require about half of a year to deliver "good" update, or you can generate "shitty" updates every two months. "Few pictures for a new girl, that has been added 6 months ago, 700 words of text, 60 new renders" - that is a typical change log for update with Unity project.
If you are not developing some 3D slasher with 4k level graphics - stay away from Unity and Unreal Engine.
This is what I've found on their website. Though I had heard the controversy that you're talking about, what it seems that they're saying is money-wise, I may have missed the 2c you said. I have also talked with a dev that uses Unity on steam, and they said that it's free unless you make this money - never told me anything about 2c per installation (which is, indeed, absurd if they're still doing that). But I have no idea, as this is as much as I have looked into it myself.
Wait, maybe those 2 last lines that I have highlighted aren't talking about annually but in total?
But even so, I didn't say Unity is the sole engine. UE engine is also free. Even if we agree that Unity is expensive, this leaves us with UE, an argueably better engine.
Anyway, I'm not even saying that they "absolutely must" change engine or something, I'm just saying that engines other than HTML (which isn't an engine even) are superior and free. Anyway, this wasn't some huge point I wanted to make or something, just more of a question. Some people, like me, had no idea that (at least UE) is free until you make a ton of money xD